Celiac disease and anorexia nervosa linked, study shows

New research from Sweden has uncovered an unexpectedly strong link between celiac disease and anorexia nervosa. The study of nearly 18,000 women with celiac disease and 89,000 controls, published this week in Pediatrics, found that women with celiac disease are at increased risk of also being diagnosed with anorexia -- either before or after the celiac diagnosis is made. Women with celiac disease were 46 percent more likely controls to later develop anorexia, and were twice as likely to have already been diagnosed with anorexia when their celiac disease was first identified.

The two diseases have different origins: Celiac disease is an autoimmune disorder in which eating gluten -- a protein found in wheat -- damages the small intestine, whereas anorexia nervosa is an eating disorder in which patients severely restrict their food intake and experience distorted body image.

The overlap could exist for several reasons, note Stanford pediatricians Neville Golden, MD, and KT Park, MD, in an editorial that accompanies the scientific study. Since both diseases have similar gastrointestinal symptoms, patients with one condition may be initially misdiagnosed with the other. Alternatively, certain genes may confer susceptibility to both diseases, or some element of one disease may increase risk for the other.

For instance, since the only effective treatment for celiac disease is to avoid all gluten-containing foods, patients with the autoimmune disease must drastically change their diets. This goes beyond avoiding bread and pasta made with wheat, since gluten sneaks into the food supply in all sorts of unexpected places -- think soy sauce, hot dogs and licorice. But eliminating a lot of foods may itself cause problems, Golden and Park write:

Not infrequently, an eating disorder begins with well-meaning, self-imposed attempts to 'eat healthily' by eliminating foods perceived to be unhealthy... The present study suggests that excessive focus on diet in patients with CD may lead to development of AN in susceptible individuals.

The study focused on people who had undergone thorough testing to confirm their celiac disease, but other individuals who are adopting gluten-free diets may also be at risk for eating disorders, they note:

Interest in 'going gluten-free' is increasing, particularly in adolescent female subjects, with 1 in 5 Americans attempting to restrict daily gluten intake. The interaction between gluten-free diets and eating disorders is an even larger issue. This important study only addresses the tip of the iceberg.

The scenario many of us learned in school is that two X chromosomes make someone female, and an X and a Y chromosome make someone male. These are simplistic ways of thinking about what is scientifically very complex.